Gruenbaum, Shaun E.

Background: Pulse pressure variation (PPV) is widely used to guide fluid responsiveness in mechanically ventilated patients, but its accuracy in the prone position remains uncertain. Prone positioning alters respiratory mechanics and venous return, potentially diminishing the respiratory variation in stroke volume that PPV is designed to detect. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of PPV for predicting fluid responsiveness during prone spine surgery. Methods: We searched MEDLINE, Embase, Scopus, and Cochrane through July 2025 for prospective studies evaluating PPV in adults undergoing prone spine surgery. Two reviewers independently screened studies, extracted data, assessed risk of bias using QUADAS-2, and pooled diagnostic performance using a bivariate random-effects model. The protocol was registered with PROSPERO (CRD420251106134). Results: Of 599 records, 34 underwent full-text review, and 10 studies (433 patients) were included. PPV thresholds ranged from 7% to 15%. Most studies were at low risk of bias except for the index test because thresholds were determined post hoc. For predicting fluid responsiveness, PPV had a pooled sensitivity of 68% (95% CI: 61%-75%) and specificity of 76% (95% CI: 65%-84%), with a summary area under the receiver operating characteristic curve of 0.72 (95% CI: 0.64-0.80). Conclusions: PPV showed only moderate diagnostic performance for predicting fluid responsiveness during prone spine surgery. Its performance may have been influenced by threshold variability, heterogeneous reference standards, fluid-challenge protocols, ventilation strategies, and positioning systems. PPV should therefore be interpreted alongside complementary dynamic assessments rather than in isolation, particularly during lung-protective ventilation.

Abstract Objective: Reading is a complex cognitive process requiring the integration of orthographic, phonological, and semantic information. The visual word form area, located in the ventral occipitotemporal cortex, is critically involved in orthographic decoding, and damage to this region is known to cause alexia. In contrast, the contributions of white matter pathways supporting reading are less well understood. Method: We present a unique neurosurgical case undergoing awake brain surgery for resection of a metastasis in the left occipitotemporal cortex. A tubular retractor was used to access the lesion and during the insertion of the retractor the patient underwent careful, continuous neuropsychological testing, including evaluation of reading. fMRI language mapping and diffusion MRI were performed preoperatively. Postoperative neuropsychological testing was completed two weeks after surgery to assess cognitive outcome. Results: The patient developed an alexia with letter-by-letter reading in real time during insertion of the tubular retractor. Stealth imaging enabled localization of the tubular retractor at the exact onset of the alexia and, by correlating this with tractography, showed that the tubular retractor was in the vertical occipital fasciculus (VOF). Conclusions: We present the first detailed case report linking the VOF to the acute onset of alexia observed intraoperatively during awake brain surgery. We discuss the connectomics of reading and possible contributions of the VOF in reading.

Background: The perioperative management of chronic aspirin therapy in patients undergoing elective brain surgery is challenging due to the risk of bleeding and thromboembolic events. Although aspirin discontinuation reduces the bleeding risk, it can increase thrombotic complications, particularly in patients at high risk of cardiovascular complications. This Delphi study aimed to develop consensus-based guidelines to address these clinical challenges. Methods: A 2-round Delphi survey was conducted among an international panel of 42 experienced anesthesiologists and neurosurgeons. Participants assessed the risks and benefits of perioperative aspirin management, including bleeding risk, thrombotic risk, timing of cessation and resumption, and the utility of platelet function testing. Consensus was defined as ≥80% agreement in round 2. Results: Round 1 highlighted significant variability in practice patterns. In round 2, consensus was reached on several key areas. Most experts (84%) agreed that continuing aspirin increases perioperative bleeding risk in high-risk procedures, with 87% recommending discontinuing aspirin 5 to 7 days before surgery. Nearly all experts (97%) supported continuing low-dose aspirin in high-thrombotic-risk patients. Conversely, for low-thrombotic-risk patients, only 65% agreed on aspirin continuation, reflecting an ongoing debate. No consensus was reached regarding routine platelet function testing. Conclusions: This Delphi study provides experience-based recommendations for managing chronic aspirin therapy in neurosurgical patients. The panel strongly supports aspirin continuation in high-thrombotic-risk patients, with cessation 5 to 7 days before high-bleeding-risk surgeries. Individualized management is advised for low-bleeding-risk procedures and low-thrombotic-risk patients. Future research should further clarify aspirin management in these groups and explore the role of platelet function testing in neurosurgical settings.

Background Medical oaths and ethical codes play a crucial role in guiding physicians through their professional responsibilities. This study extends prior research on ethical codes created by students at the Medical School for International Health (MSIH) by analysing codes from the years 2007 to 2022. Objective The objective of this study is to evaluate changes in the ethical principles emphasised by MSIH students over time and to compare these with previous cohorts. Methods Ethical codes from MSIH classes (2007–2022) were analysed using the framework developed by Baker. This framework categorises oaths into four sections: preamble, covenant, code of duties to patients and peroration. The focus was primarily on the code of duties to patients. Quantitative analysis was used to assess the prevalence of specific ethical principles. Results The study found an increased emphasis on principles such as ‘respect for patients’ and ‘cultural competence/sensitivity’, while traditional values like ‘benevolence’ and ‘honesty’ were mentioned less frequently. New themes, including ‘patient autonomy’ and ‘cultural competence’, emerged, reflecting a shift towards patient-centred care and justice, though emerging issues like artificial intelligence ethics were not addressed. Conclusions MSIH students’ ethical codes have evolved to emphasise patient respect and cultural competence. The findings suggest a maturation in the ethical perspectives of medical students, though gaps remain in addressing contemporary challenges. Future studies should explore how ethical codes can incorporate emerging issues in healthcare.

Study Design. Literature review and institutional analysis. Objective. This review examines the potential advantages of awake spinal surgery under neuroaxial anesthesia in minimizing positioning-related complications compared with traditional general anesthesia. Summary of Background Data. Spinal surgeries performed in the prone position under general anesthesia are associated with perioperative complications, such as ocular injury and vision loss, nerve damage, and pressure ulcers. Materials and Methods. A comprehensive literature search was conducted for articles published from 1986 to 2023 focusing on awake spinal surgery and positioning-related complications. In addition, insights from the Mayo Clinic team were incorporated to assess the potential benefits of awake spine surgery. Results. The review identified several positioning-related complications associated with prone positioning during spine surgery, including perioperative visual loss, neuropathies, pressure ulcers, and intra-abdominal hypertension leading to systemic cardiovascular effects and potential organ dysfunction. Advances at the Mayo Clinic have enabled the use of awake spinal surgery under neuroaxial anesthesia for complex procedures such as robotic transforaminal lumbar interbody fusion. The use of awake lumbar spine surgery has demonstrated advantages, including reduced positioning-related complications, immediate patient feedback to avoid harmful maneuvers, shorter operating room times, and improved hemodynamic stability. Conclusions. Awake lumbar spine surgery offers notable advantages in reducing positioning-related complications and presents a promising alternative to general anesthesia.

AbstractAbsence seizures (AS), presenting as short losses of consciousness with staring spells, are a common manifestation of childhood epilepsy that is associated with behavioral, emotional, and social impairments. It has also been suggested that patients with AS are more likely to suffer from mood disorders such as depression and anxiety. This systematic review and meta‐analysis synthesizes human and animal models that investigated mood disorders and AS. Of the 1019 scientific publications identified, 35 articles met the inclusion criteria for this review. We found that patients with AS had greater odds of developing depression and anxiety when compared to controls (odds ratio = 4.93, 95% confidence interval = 2.91–8.35, p < .01). The included studies further suggest a strong correlation between AS and depression and anxiety in the form of a bidirectional relationship. The current literature emphasizes that these conditions likely share underlying mechanisms, such as genetic predisposition, neurophysiology, and anatomical pathways. Further research will clarify this relationship and ensure more effective treatment for AS and mood disorders.

Background: During awake craniotomy, securing the patient’s airway might be necessary electively or emergently. The objective of this study was to compare the feasibility of airway management using a laryngeal mask airway (LMA) and 4 alternative airway management techniques in an awake craniotomy simulation. Methods: After completing a questionnaire, 9 anesthesia providers attempted airway management in a cadaver positioned to simulate awake craniotomy conditions. Following the simulation, participants rated and ranked the devices in their order of preference. Results: Only 3 approaches resulted in the successful securement of an airway device for 100% of participants: LMA (median; interquartile range time to secure the airway 6 s, 5 to 10 s), fiberoptic bronchoscopy through an LMA (41 s; 23 to 51 s), and video laryngoscopy (49 s; 43 to 127 s). In contrast, the oral and nasal fiberoptic approaches demonstrated only 44.4% (154.5 s; 134.25 to 182 s) and 55.6% (75 s; 50 to 117 s) success rates, respectively. The LMA was the fastest and most reliable primary method to secure the airway (P=0.001). After the simulation, 100% of participants reported that an LMA would be their first choice for emergency airway management, followed by fiberoptic intubation through the LMA (7 of 9 participants) if the LMA failed to properly seat. Conclusions: We demonstrated that an LMA was the fastest and most reliable primary method to secure an airway in a laterally positioned cadaver with 3-pin skull fixation. Fiberoptic and video laryngoscope airway equipment should be readily available during awake craniotomy procedures, and an attempt to visualize the vocal cords through the LMA should be attempted before removing it for alternative techniques.